From: Mariel Cherkassky <mariel(dot)cherkassky(at)gmail(dot)com>
To: pgsql-performance(at)lists(dot)postgresql(dot)org
Subject:
Date: 2019-04-02 08:32:23
Message-ID: CA+t6e1=frX3TrLbsJY1jWBsJ0AACHjqp1FCKq=WQHvNjc=gNSg@mail.gmail.com
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Hey,
I wanted to a few questions regarding the parallel parameters :
max_worker_processes and max_parallel_workers_per_gather.

1)Basically, max_worker_processes should be set to the number of cpus I
have in the machine ?
2)If I set max_worker_processes to X and max_parallel_workers_per_gather to
Y (X>Y) it means that I will have at max (X/2) queries that can run in
parallel. Am I right ? For example, max_worker_processes
=8,max_parallel_workers_per_gather =4, it means that at max I can have 4
queries that are running in parallel ? and at min 2 queries (or none) can
run in parallel ?
3)So If I calculate my work_mem based on the number of sessions I have :
(TOTAL_MEM/2/NUM_OF_CONNECTIONS)
I should add 8 to the NUM_OF_CONNECTIONS to have a new value for the
work_mem in order to consider queries that run in parallel..

Thanks.

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